Illidan's going to be a Master Hero. At first glance, they play like most any other card. They start off in your deck, and they get shuffled into your hand as normal. However, when you can afford the resources to bring Illidan into play, he replaces your existing hero. He starts off with same states and effects as the hero he replaces -- this includes any counters and damage, or other effects like Gouge.

Of course, folks on the TCG forums aren't entirely convinced of Illidan's uberosity. As Zubino points out, you have to wait at least until turn 11 to get him out. If you're stalling until turn 11, then you need a whole lot of other oomph in your deck to be able to prop up the card. Still, being able to call out a Traitor ally every round is a nice ability, and we can all hope to boost him up a little more with Warglaives. And don't forget -- 35 health is nothing to sneeze at in a Hero card.

The Master hero definitely brings another facet of play to the TCG, which is about more than just the loot cards. Of course, now I have to wonder who the next Master hero will be.